Heretofore, many methods for producing a catalyst component-carrying titania fiber are known. For example, JP-A-5-184923 discloses that a vanadium oxide-carrying titania fiber is obtained by heat-treating an amorphous fiber to transform a crystal of an anatase-form titanium oxide and a crystal of a vanadium oxide. In this method, the amorphous fiber was produced by a sol-gel method of hydrolyzing an alkoxide in a solution of a titanium alkoxide and a vanadium compound or hydrolyzing alkoxides in a solution of a titanium alkoxide, the other alkoxide and a vanadium compound, followed by gelation.
JP-A-6-134306 discloses that a catalyst component-carrying titania fiber is obtained by forming a polymer containing titanium and silicon which is made from organic alkoxides of a titanium alkoxide and a silicon alkoxide by a sol-gel method, spinning to form a fiber, drying and calcining the fiber to obtain a titanium oxide-silica fiber, and carrying vanadium oxide and/or tungsten oxide.
However, the catalyst component-carrying titania fibers obtained by these methods have problems in that, since the specific surface area and the pore volume of the fibers are not so large, the catalyst activity of the fibers is not so high, resulting in low performances of the fibers, for example, in reduction of nitrogen oxides, oxidation of organic compounds, decomposition of dioxin or decomposition for removal of chemicals such as organic solvents, agricultural chemicals and surfactants in water.